Apparently the Mr. Microphone phenomenon started earlier than I thought. Here's the BMS Home Broadcaster, which allowed your voice to go over the radio from as far away as the wire would stretch.
It looks like a carbon microphone hooked to wires, which you then attached to these induction coils, which you placed between the tube and its socket:
Here's the instructions, click to enlarge.
The technology changes, but our sense of humor never gets anymore sophisticated.